Safety-fuse.



PATENTED JUNE 11, 1907. W. J. PHELPS. SAFETY FUSE.

APPLICATION FILED Mn 4. 190s.

f; f f/ PH ELPS INVENTOR 4o i beinglmade of glass or mica,

f and State of Michigan, a

UNITED sT-ATEs AiATnNT onirica.

WILLIAM J. PHELPS, OF DETROIT, MICHIGAN.

SAFETY-FUSE'.

-`ments, and consists in the novel construction of a fuse of i this. character adapted to indicate visually latter has been disrupted by an excess of current.

.The invention further consists in the peculiar arrangement and combination of the various partsof the fuse and in other details of construction as will be more fully hereinafter y described.l

' .Figure'l is a vertical In the drawings illustrating my invention, central lsection through a safety fuse made in accordance with my in-y vention. Figs. 2 to 9 inclusive are modifications of the construction shownin Fig. 1. Fig. is a section through a fuse embodying my invention `rial, as for inst ance e means for lntershowing t disruption rupting the arc formed `upon the ofthestrkip. Fi .n is @View Similar to Fig, 10 showing adi erent method of interrupt- -ing the arc. Fig. 12 -is a modified construction of fuse' especially adapted for use in high potential circuits, and Fig. 13 lis a further' modiication of a safety fuse showing a novel ty e of fuse strip.

n thel drawings thus brieiiy referred to7 reference beingphadto Fig. l1, A represents an.

inclosing casing in this instance transparent, sealed at its ends e plugs B and() of any suitable mateplaster paris. D and E re resentrespectively the terminal'wires or wfiat will be hereinafter referred to as the terminals, sealed in the plugs as shown. F is a fusible conductor preferably a copper wire ofthe proper section or the ordinary lead alloy known as fusewire connected in any suitable manner as by soldering to the terminals.

It is desirable for y sons to have an inclosed fuse ofthe kind just' described constructed in such manner as to 'show plainly the condition of the fuse strip,

whether the same is in operative condition or Specification of Letters Patent. Application filed May 11,1908. Serial No. 155,658.v

l the fuse and which changes the condition of the fuse strip or the fuse conductor, particularly when the -of ammonium carbonate and water.

`rior of the cover may portion of the inner casing 1n various well known real U coated with Patented June 11,1907.

is disrupted; For this (purpose I have shown J. PHnLPs, in the' figure referred to an annular portion of the transparent casing coated upon the intet rior with material G which has an affinity for the gases evolved upon the disruption or what is generally termed the blowing of color when the disruption occurs. Various materials may be employed to produce the desired result and the composition of the fuse strip may be varied with reference to the chemical affinity of the indicating material. Ordinary sulfur changes color and becomes dotted with black specks.` One arrangement which I have found very effective in connection with a copper fuse is to coat the inside of the indicating area' with a thin paste This looks white, before blowing, and changes to bright blue on the disruption of the fuse. A gas may also be` employed such as 'sulfureted hydrogen which has an affinity for copper oXid.

In Fig. 2 a modified form of casing is illustrated being formed of porcelain and having a single inspection opening Q formed cen` trally within the casing, which is closed by a transparent cover J.

' be coated as at K with an indicating material.

Afurther modiiication is illustrated in Figs.

In thiscase the inte- 3 and 4'where a double or compound casing.

is employed consisting of section L and an outer shell M other opaque material inclose the transparent section. The exposed this instance is coated with a color changing material as rindicated at O.

In Figs. 5 and 6 I have shown the casing in the form of a porcelain trough P rectangular in form and provided with a top Q of glass of wood or i coated interiorly as at R with material that will change color as the fuse blows.

an inner transparent adapted to partially IOO In Fig. 7 the casing S is semicircular in configuration.

The ordinary fuse plug T of the Edison type may also be made to indicate. A construction of `indicating fuse of this character is shown in Fig. 8 wherein the plug is -open at its top and covered with ay transparent plate the material described, vdesignated by the reference letter i A still further modification with respect to the casing is illustrated in Fig. 9, the casing being ofthe compound type consisting of the The portion of inner tubular transparent section W and a similar inclosing section X of opaque material having an inspection opening Y through which the interior of the fuse may be.viewed.

site the inspection opening described is coated in this instance as indicated at 71. .f

It is desirable to provide means Within the fuse for interrupting the arc, which otherio wise mig t follow the disruption of the fuse strip when used on circuits of ordinary voltage. i One form -of interrupting means is shown in Fig. consisting of the oppositely extending cones A and B asbestos and sealed 'withinthe ends of the 2o the fuse combined With the z 5 a quick eXpulsive blast follows the casing C by the plugsD. The fuse strip in thls instance extends through both cones and connects with the terminals in the usual manner. The gases evolved upon the blowingof expansion of the air from the heat produced, create a pressure in the space between the cones A and B the only outlet for which is through their apices inthe opening lately occupied by itself.' Thus blowing of the fuse which actsy mechanically to force back in bothdirections and prevent the formation of an arc.J

In the constructionshown` in Fig. 11 the 3o interruption of 'the arc 4depends either on chemical affinity or on mechanical absorption and cooling or on these causes combined. When a fuse breaks `down under an excess of current there is left for an instant a path of hot gas between the terminals which. offers 4o very rapidly with the 5o per and which at once by ,consists of the transparent casing relatively low resistance and invited a continuation of the current, Which the fuse was pu't there to interrupt. This is the arc above mentioned. The danger of arc increases increase of F. The ease and certainty with which an arc ma 'be prevented or instantly suppressed ancfr the fact that the'meltedmetal or gases evolved are wholly confined and revented from doing damage when a fuse b inclosed type. In Fig. 11 a copper fuse may be surrounded by some material such as chlorid of lime .which has an affinity for copchemical combination removes the path of hot metal or gas. Or ya filling such as asbestos may be used which acts like a blotting paper to absorb and cool the gases. Asbestos may be impregnated with ammonium carbonate solu tion or mixed with the dry powdered ammonium carbonate and `then' mechanically interrupts the arc and chemically changes color and indicates.

The safety fuse shown in Fig, cially designed for high lpotential circuits and minals H', a hollow core I preferably of loosely woven asbestos extending longitudinallywithin the casing having its ends sealed the transparent `casing Ioppof formed of fiber or.

ows consti tute the chief advantage ofthe cartridge or.

in the plugs J', and a spiral fuse strip K which is wound about the core in'the manner illustrated, its ends being connected to the terminals. Within each end of the casing and surrounding the fusible conductor and the core, is arc interrupting material L', which in this instance may be plaster of paris. The quantities of material are spaced apart so as to form an opening M at the center, and the interior or transparent casing at this point may be coated as at O.

y In Fig. 13, a construction of safety fuse is shown wherein the indication is made by the black oxid oflcopper formed upon the dis ruption of the fuse, which collects and thus in icates upon the transparent casing. In this modification the tube P is of glass, and in the ends are sealed the terminals 2 by preferably melting the ends of the tube.

Small apertured disks R and S are inserted within the interiorofthe tube and serve to keepin the tube ends the filling material T whichv acts to interrupt the arc. As thus constraucted an air space U is formed centrally in the tube and upon the'blowing of the fu/se the black oxid of copper collects in this space and is deposited upon the interior of the transparent casing at this point thereby indicating the condition of the device.

It has been the general practice heretofore to connect the terminals of the fuse bythe ordinary fuse strip, the joints being formed by soldering. I have devised means for constructing thefuse in a manner which will perform the same results and can be manufactured at considerable less cost. To accomplish this result I make the fuse strip and terminalsin one piece of the same cross section throughout its length, the strips being preferably copper. The ends ofthe strips I make of relatively higher conductivity than the central portion thereof or fuse proper.

A convenient maner of doing this is to coat the ends of the strip with copper.

.What I claim as myy invention is:

1. InI a safety fuse, the combination with a casing closed throughout, of a fuse strip inclosed therewithin, and means connected to the inner surface of the casing and acting automatically. upon the disru tion of the fuse for indicating the disrupte condition of the strip.

2. In a safety fuse, the combination with a fuse lug constituting al casing sealed throng out, of a fusible conductor therein, the top of said plug being formed of transparent material and constituting an inspection opening, and a coating of indicating material mounted directly upon the inner surface of said top adapted to discolor upon the disruption of the indicator.

3. In a safety fuse, the combination with a fuse plug constituting an inclosing casing, a portion of the inclosing casing being transparent, of a fuse strip within the casing, and

IlG

IIS

means Within the plug connected directly to dicating material applied directly upon its Io the inner surface of said inclosing casing and inner surface and separated from the strip acting automatically upon the disruption of for indicating the disruption of the fuse.

the fuse for indicating the disrupted condi ln testimony whereof l aliX my signature tion of the strip. in presence of tWo Witnesses.

4. In a safety fuse, the combination With a WILLIAM J. PHELPS. fuse plug comprising sides and a bottom, of a Witnesses: transparent top therefor, a fuse strip Within ESTELLE WORTMAN,

the plug, and said top having a coating of inl CORA PEARL BLIss. 

